In a power system, conventionally, power has been supplied mainly by a power generation method in which fossil fuel is used such as thermal power generation. In recent years, from the viewpoint of climate change and energy security, distributed power supplies and renewable energy power supplies have been increasing. However, outputs of the renewable energy power supplies considerably depend on weather and easily change. Therefore, according to the increase of the renewable energy power supplies, there is concern about deterioration in power system quality and adverse effects on stable supply.
As measures against these problems, it is possible to reduce the deterioration in the power system quality and the adverse effects on the stable supply through introduction of power system equipment (hereinafter described as device) including a FACTS (Flexible AC Transmission System) device and a storage. Extension of transmission lines is expensive and requires several years as an extension period. On the other hand, installation of the FACTS device and the storage is inexpensive compared with the transmission line extension and has less influence on the environment.
A power company, a TSQ (Transmission Systems Operator), and a DSO (Distribution Systems Operator) can determine installation places and introduction capacities of the FACTS device, the storage, and the like on the basis of detailed information concerning a power system such as operation information of devices and the size of power demands (NPTL 1).
NPTL 2 discloses a method of evaluating stability of a power system using indexes called “net-ability” and “entropy degree” on the basis of a complex network theory.